Pneumatic treadle control mechanism



@do 9, 1934. R D CQNKLIN PNEUMATIC TREADLE CONTROL MECHANISM l Rv.m tA MM w Mn @KU V0 f ma. .t w z .n 0 s u 5 0 Filed Aug. 4. 1935 A TTORNE YS.

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PNEUMATIC TREADLE CONTROL MECHANISM Filed Aug. 4, 1933 .3 Sheets-Shea?I 5 f :1.5 M so "L 45* p. 58?

v INVENTOR. @05mg '0. Con HJM Patented @et Q9 E9 E'l Y PNEUDIATC TREDLE CONTROL MEC SM oe Conklin, Railway, N. I., assiguor to National Pneumatic Company, New York, N. Y., a corporation ci West Virginia Application August 4, 1933, Serial No. 683,609

ZCiaims.

jihis invention relates to improvements in pneumatically operated door mechanism of the treadle controlled type' involving the use oi a pneumatic treadle for controlling the pneumatic 6 operating door apparatus.

An object of this invention is to provide an improved form of pneumatic treadle control Vin which a compressible treadle lcontrols an air stream in which variations in the pressure thereof as produced by the application of pressure to the treadle eiiects a control of mechanism which in turn controls the door operating mechanism.

A further object of this invention is to employ a pneumatic treadle which through the intermediate agency of either electro-pneumatic orv straight pneumatic mechanism controls the operation of other devices such for example as door operating motors.

These and many other objects as will appear 2o from the following disclosure are secured by means of this invention. This invention resides substantially in the combination, construction, arrangement and relative location of parts,all as will be described in greater detail in the following specification:

Referring to the drawings:

Fig. 1 is a top plan view of the improved pneumatic treadle ofthisl invention;

Fig. 2 is a transverse cross-sectional view thereof;

Fig. 3 is a diagrammatic illustration of one form of control mechanism employing the pneumatic treadle; 4

Fig. 4 is an elevational view of the pressur operated switch;

Fig. 5 is a cross-sectional view taken on the line 5 5 of Fic. 4:

Fig. 6 is a diagrammatic illustration of a modiiled lform of straight pneumatic apparatus;

Fig. 'l is a vertical central cross-sectional view through the mechanism for operating ,a control valve through the agency of the pneumatic treadle;

Fig. 8 illustrates diagrammatically the change necessary to operate the apparatus on vacuum as distinguished from the previously described pressure operated types;

Fig. 9 is an elevational view of the vacuum operated switch;

Fig. 10 is a cross-sectional line 10-10 of Fig. 9; l

Fig. l 1 illustrates diagrammatically the changes necessary to operate the straight pneumatic type view taken on the 45'5 on vacuum as distinguished from the corresponding previously described iluid pressure operated type; and

Fig. l2 is a view partly in vertical cross section v and partly in elevation of the vacuum operated mechanism for actuating a control valve.

It-is common practice in the operation of transportation systems, such as subways, busses and the like, to provide treadle control mechanism for the doors of the vehicle. It is also common practice to employ treadle control mechanism for opening and closing doors in buildings. 'I'he most commonly used types of treadle control employ a control switch or valve which is directly operated by movements of the treadle usually placed adjacent the door to be operated. s@ A purpose of this invention is to provide an. improved form of pneumatic treadle which may be likened to the prior arttype in which the treadle plate directly actuates a valve. However, with the mechanism of this invention,v a 75, much simplified structure is provided and one which is rugged and dependable in operation.

In the present invention a collapsible tube such as for example, a soft rubber tube, through which a uniformly ilowing stream of air passes l@ either under pressure greater than atmospheric or less than atmospheric pressure forms part of the treadle which is connected to control mechanism which will be actuated when the movement of this stream is interrupted by pressure applied to the treadle. There are disclosed herein several forms of apparatus controlled by such a treadle which may broadly be divided into classes of electro-pneumatic control and straight pneumatic control.

Referring to the drawings, the invention will now be described in full detail. The treadle structure is generally indicated at 1 in Figs. 1 and 2. It comprises an upper tread plate 2 and a base plate 4 which are preferably made of a exible material such as rubber, rubberized tabric and the like. Thetread and base plates are secured together around 'the edges to provide a closed compartment and are held in spaced relation by means of the strips 5 which may be made of any suitable material but preferably of a stili relatively hard rubber so that' parts may be vulcanized together.

'l'he forward edge of the tread plate is formed at right angles to the plane thereof and is preferably of thicker cross-section as indicated at 3 toform a nose which ts over the edge of the step adjacent the door to be controlled. Interposed between the plates of the treadle at spaced points are the soft or compressible rubber stripsl no loo los'

6 which act to normally hold the plates in proper spaced relation. Distributed in any suitable manner within the compartment of the treadle is a soft flexible tube 7, preferably made of soft rubber, which opens at the end 7' directly into the atmosphere. The other end of this tube extends to the apparatus to be controlled as indicated for example in 3. As shown in this gure, the tube extends to a iiuid pressure operated switch indicated generally at 8, having a connection 9, which extends to any suitable iluid pressure source. The contact disc 10 of the switch is positioned to engage two fixed contacts, one of which is v,connected by Wire 11 to the magnet valve 12. The other terminal of this valve is connected to one terminal of a current source 14 which has its other terminal connected by wire 15 to the other fixed contact of the switch. The pipe 16 connects the lcontrol valve to a suitable fluid pressure source, and the pipe 17 extends to the device to be controlled, such as for example', a door operating motor.

The structure of the iiuid pressure operated switch, as clearly shown in Figs. 4 and 5, comprises a base portion 18 and a cap portion 19 secured thereto. Firmly sealed between the parts 18 and 19 is a flexible diaphragm 20 to which is secured in accordance with well known practice,

a stem 25 on which the contact 10 is slidably and resiliently mounted. The fixed contacts to be interconnected by the contact plate 10 are 'mounted on a suitable insulating support 27.

The base portion 18 is provided with a series -of converging passages as is clear from Fig. 5, which'are connected by a vertical passage with the chamber in which the diaphragm 20 operates.

The passage '1" is the one to which the flexible tube of the treadle 7 connects. The passage 9" is they one to which the pipe 9 from any suitable fluid pressure source connects. An adjustable needle valve 21 controls the rate of ow of uid pressure from the source to the pipe 7. 'I'he iinal passage is closed by means of an apertured plug 22, and in this passage is a ball check valve 24 which is normally held seated by means of a spring 23. Y

In the operation of this device a stream of air under a pressure from one toetwo pounds per square inch is delivered from the source through pipe 9 vpassed the needle valve 21'- through connection 7" to the tube 7, from which it issues through the open end 7'. When there is no pressure on the treadle and with the contacts pro erly adjusted, the air ilow is effected without causing the diaphragm to move out of the position shown in Fig. 4 in which position it isheld by the spring 26 pressing on the upper surface thereof. However, as soon as pressure is applied to the tread plate of the treadle the soft rubber tube 7is collapsed at one or more points with the result that the airflow therethrough is cut oil? or reduced.

,This action causes a back pressure to .build up under diaphragm 20 with the result that it rises, compressing spring 26 and moving contact 10 into engagement with the iixed contacts. This completes the circuit to magnet valve 12 which controls the door engine, or any other device connected thereto. The magnet valve 12 is illustrated diagrammatically because it is very old and well known in this art. It may be noted, however, that it consists of a solenoid operated plunger which controls a valve of the structure clearly shown in Fig. 7. Thus the solenoid when energized would move a plunger causing the Valve exceeds a safe value this pressure will be relieved through the port in plug 22.

The straight pneumatic type shown in Fig. 6 employs the treadle of Fig. 1. In this case the pipe 7 connects to the small fluid pressure engine 30 which has a piston rod engaging with the lever 32 pivotally mounted on the bracket 34. `The other end of lever 32 engages the valve stem 35 from the valve 36. This mechanism is shown in detail in Fig. 7. The small engine which operates the valve comprises a base plate 39 and a cover plate 40 between which is sealed the diaphragm 41 within a chamber. The piston rod or stem 33 is connected to the diaphragm and extends through the casing to engage it with the lever 32 pivotally mounted on the bracket 34. A spring 42 rests on the upper surface of the diaphragm and pivoted lever 32.- The passage 38" is connected by pipe 38 to a suitable uid pressure source. The passage 37 which opens into the casing of the valve between seats is connected by the pipe 37 'o the device to'be controlled, such as a door motor.

' As before, iuid under pressure from one to two pounds per square inch ows from the source through pipe 3l through the passage in the valve 30 to tube 7yand thence to the atmosphere through the open end 7". When the ilow of air through tube 7 is cut olf by pressure applied to the treadle, diaphragm 41 rises with the result that valve 60 unseats from the upper seat and seats on the lower seat. This cuts off the supply of fluid pressure from pipe 38 to pipe 37 and connects pipe 37 to the atmosphere through the exhaust port 43 of the valve. Of course, as pointed out before this operation of the valve may establish a connection between pipes 37 and 38 rather than cut ofl a connection therebetween.

`The invention may also be applied to a socalled vacuum system which is really a iluid pressure system operating below atmospheric pressure. In

such operation it is only necessary to reverse the thereof, holding contact plate 10 above the ilxed' contacts. Passage 17" is connected by pipe 17 to the ,vacuum source. Passage 7" is connected to the tube`7 of the treadle. As before, the adjust- 1 able needle valve 21 controls the movement of air from 17" to 7". In this case when tube 7 is closed by pressure on the treadle, the vacuum source will reduce the pressure under diaphragm 20 causing it to move downwardly compressing spring 26. This causes contact plate 10 to close thevcircuit connected to the xed contacts.

The full pneumatic arrangement is illustrated in Figs. 1l and 12. In this case the spring 42 presses on the-lower-surface of diaphragm 41 holding it in raised position asv indicated in Fig. l2. In this case the bracket 34 pivotally supports lever 32 at one end and is pivotally connected to the stem 33 mounted on the diaphragm. The passage 17 is connected to the vacuum source and the passage 7" is connected to the exible tube 7. The needle valve 2i is employed as previously described. When the movement of air through tube 'I is cut off a vacuum condition is created under diaphragm 41 so that it moves down wardly causing valve 36 to operate as previously described.

From the above description it will be apparent that this invention resides in certain principles of construction and operationas illustrated in the drawings. It is recognized that those skilled in the art may readily vary the application of these principles and the structure by which they are applied without departure from the scope of this invention. I do not, therefore, desire to be strictly limited to the disclosure as given for purpose of illustration, but rather to the scape of the appended claims.

whatrseektumeur-emiUnitedStatesLettersY Patent is:

1. The combination as described comprising a control device, pressure fluid operated means for actuating the control device, a pressure lluid source connected to said means and a compressible treadle forming a pressure fluid conduit with and connected to said mean' and open to the atmosphere so that iluid normally ows through the conduit, whereby when pressure is applied to the treadle the conduit isiclosed and a back pressure is created to operate the pressure fluid operated means.

2. The combination as described comprising a comprefssble treadle having an air passage therethrough which is normally open to the atmosphere and which closes when the treadle is compressed, means for creating a continuous flow 015V air through said passage, andvpressure iluid actuated means connected to said means, whereby when the aixpassage is closed the flow of air therethrough is ct ol and said pressure uid actuated means is operated.

' ROSCOE D. CONKLIN. 

